By looking at a few paragons and A grade Bakers I can see my cocking lever is not shaped properly to easily go under the cocking rod. Once the barrels are attached what I have done is taken a small wood dowel and pushed the cocking lever under the cocking rod and then all works fine. I suppose what I must do is attempt to reshape the cocking lever so it doesn't bind up against the cocking rod.

Nothing is foolproof to a sufficiently talented fool.